Alkali-metal sulfite-digested redwood bark solubles



ik ai Patented Apr. 6, 1954 ALKALI-METAL SULFITE-DIGESTED REDWOOD BARK SOLUBLES Harry F. Lewis and Mario 11 A. Buchanan, Appleton, Wis., assignors to The Pacific Lumber Company, San Francisco, Calif., a corporation of Maine No Drawing. Application April 11, 1951, Serial No. 220,528

2 Claims.

The present invention relates generally to a new composition of matter derived from the treatment of redwood bark. More specifically, the present invention relates to a new composition consisting essentially of the alkali salts of sulfonated redwood bark.

Bark from the California redwood, i. e., a'soft wood or conifer known as Sequoia semperm'rens, has for the most part been considered a waste material of little economic value. The bark contains a relatively high percentage of complex chemicals (as evidenced by the resistance of the redwood tree to decay) and is made up of about equal proportions of redwood bark fibrous material and redwood bark dust containing unique high molecular weight phenolic acids characterized by their relatively high content of acidic carboxyl groups and negligible content of methoxyl groups. The disposal of the redwood bark has constituted a problem in the redwood lumber industry for many years.

The principal object of the present invention is to provide the industry with a useful product derived from the bark of the redwood tree. Other objects and advantages of the present invention will be apparent from the following description.

In carrying out the present invention, redwood tree bark or its components (redwood bark fibrous materials and redwood bark dust) is treated with an alkali metal sulfite to produce a product or composition having commercial utility in various fields. The process preferably employed comprises cooking the redwood bark, preferably in the form of chips or other comminuted form, in an aqueous alkali sulfite '(e. g. sodium sulfite or bi-sulfite) cooking liquor .until the complex bark acids are solubilized and separating the resulting insoluble fibrous material from the cooking liquor. The fibrous material which is removed from the cooking liquor is made up of the bark fibers, lignin, and a pectinlike material which has been modified by the sulfite cooking treatment, as well as other insoluble chemicals. The separated cooking liquor contains the soluble chemicals which have been modified by sulfite cooking treatment including \alkali metal salts of sulfonated redwood bark organic acids. These alkali-metal sulfite-digested redwood bark solubles are adapted for use in a variety of fields. While concentrates of the cooking liquormay be used under .most conditions, it ispreferred to isolate the solubles as a solid material by evaporating the cooking liquor and then drying.

2 The following example of a preferred method of operation will serve to illustrate the present invention:

Example About parts by weight .of redwood bark chips is first placed in a .digester. .About 500 parts of a cooking liquor madeupof water containing about 15 parts of sodium sulfite in solution is then added to the bark. The resulting mixture is then cooked .at a temperature .of about C. forabout 1.5 hours. .At the end of the cooking period the digester is discharged into a blow pit where thesodiumsulfitedigested redwood bark pulp is separated from the @cooking liquor. The cooking liquor -.containing the sodium sulfite digested redwood bark solubles and made up for the most part .of sodium salts of the sulfonated redwoodbark acids is .evaporated to a solids content of about 20-25 .per cent and then dried. Before use, the fibrous :pulp is preferably washedwith water and the washing water recovered and used to make up the liquor for the next cooking operation.

It will be understood in the example, where the ratio of liquor to solids is about 5.11, that other ratios may beemployed. .Suflicient water should, of course, be used .to bring .the cooking liquor containing the sulfite .salt into contact with the bark. It will also be understood in the above example, where the ratio of bark to the sulfite salt is around 6.611, thatother ratios may be employed. Investigations, however, show that this ratio should not be greater than 20:1, 1. e., that at least about :5 per cent sulfite salt should be used based on the weight of the bark. In most cases, the use .of 1.0-20 per cent sodium sulfite based on the weight of the bark is preferred. Larger amounts of sulfite salt, however, may be used if .desired, although the use of excessive material over .and above about 25 per cent sulfite salt based on .the weight of the bark does not result in an improvement in the properties of the reaction product.

The cooking temperatures and times may be varied with low cooking temperatures requiring longer cooking periods and higher cooking temperatures requiring shorter cooking" periods. Investigations in this connection show that for most commercial operations a temperature range of about 90-170 C. is satisfactory for carrying out the cooking operations. The use-of temperatures below 90 C. requires relatively long .cooking periods before the chemicals which are to be ,solubilized .become solubilized at which .time the bark structure disintegrates upon working) while the use of temperatures above 170 C. tends to deleteriously afiect desired properties of the reaction product.

In place of sodium sulfite in the above example, other alkali sulfite salts, such as potassium and ammonium sulfites and bi-sulfites may be used. When a bi-sulfite salt is used as the alkali metal sulfite salt in place of a salt such as sodium sulfite, more salt is required to sulfonate and solubilize the bark chemicals, i. e., achieve the same degree of cooking. The solubility of the alkali metal salts in water is an essential characteristic of the sulfite reaction product. The alkali metal sulfite salts may also be used in combination with alkali metal hydroxides, one of the preferred mixtures being made up of 5 per cent sodium hydroxide and 20 per cent sodium sulfite based on the weight of the bark.

The alkali metal sulfite digested redwood bark solubles have been adapted for use in various industries including well drilling, leather tanning, and the manufacture of storage batteries. The use of the alkali-metal sulfite-digested redwood bark solubles in the particular fields enumerated are set forth below.

Alkali-metal sulfite-digested redwood bark solubles are useful in drilling muds. The use of such solubles in well drilling is disclosed and claimed in our copending application Serial No. 216,094, filed on March 16, 1951, and assigned to the assignee of the present invention. It customary, particularly in rotary drilling, to drill with the aid of a circulating drilling fluid or mud which carries away the chips of loosened material or cuttings; which cools and lubrioates the drill; and which, because of its hydrostatic pressure in the drill hole, serves as a means for controlling high pressure gas, oil, or water flows. In addition, the mud forms a thin cake about the walls of the hole which minimizes the flow of liquid (drilling mud, oil, etc.) from the hole into the strata which is being drilled.

It has been found that the addition of alkalimetal sulfite-digested redwood bark solubles to drilling muds improves certain of the physical properties of the drilling muds. The soluble alkali metal sulfite reaction product is combined with a drilling mud selected in accordance with existing conditions and desired result. For example, the mud component employed may be Ventura gray clay, Frazier Mountain clay, Texas shale mud, etc. The optimum amount of the alkali metal sulfite redwood bark reaction product added to the mud also varies in accordance with the existing conditions and desired results, although it is ordinarily employed in relatively small amounts based on the proportions of clay employed in making the complete drilling mud. Based on the dry material, the sulfite-bark product usually is added in amounts from about /2 to 1 lb. per barrel of drilling mud, but smaller or larger ratios may be used for specific clays or purposes. A homogeneous mixture of the alkali metal sulfite-bark product in an aqueous suspension of clay may be prepared prior to its introduction into the drilling hole, but in any event, a homogeneous mixture should result.

Alkali-metal sulfite-digested redwood bark solubles are also useful as battery plate expanders. Secondary cells or storage batteries consist basically of lead electrodes immersed in a dilute solution of sulfuric acid. The electrodes are usually constructed in the form of grids which are filled with a paste of lead oxides. On sending a current through the solution electrolyexcellent results.

sis takes place with the consequent formation of spongy lead at the cathode and lead peroxide at the anode. When the electrodes are interconnected by an external wire, electrons flow from the lead plate to the peroxide plate, forming lead sulfate at each of the electrodes.

When a storage battery is placed under a load, there is a gradual depletion in the quantity of lead and lead oxide which is present at the surface of the electrodes. Since th voltage of the battery depends on the amount of Pb and PbOz which is in contact with the acid in the storage battery, this depletion of Pb and PbOz on the surface of the electrodes causes the voltag of the battery to fall. To compensate for this depletion in the quantity of lead and lead oxide at the surface 'of the electrodes, various compounds, referred to as battery expanders, have been added to the paste of lead oxides in the electrodes. These compounds are characterized by their ability to expand as their lifetime increases. This expansion increases the porosity of the electrodes, thereby allowing the acid to get into the interior of the electrodes. By this means, the life of the battery can be appreciably extended beyond the point which is possible without the use of a battery expander in the electrodes.

Alkali-metal sulfite-digested redwood bark solubles provide a useful battery expander composition. When the soluble alkali metal sulfite reaction product is added in small quantities to the lead oxides in the electrodes of a storage battery, the lif of the battery when subjected to continuous load is materially increased. The quantity of battery plate expander added to the lead oxides depends on the exact composition of the lead oxides and on the expected current of the battery.

A standard operational test for storage batteries, in conformance with S. A. E. specifications, is to operate the battery at a current drain of 300 amperes and at a temperature of 0 F. until the voltage of the battery drops to one-half its original rated value. This test is commonly referred to as the cold test. This test was applied to two series of storage batteries, which batteries differed only in the battery expander compositions in the electrodes. One of the series of batteries contained a standard battery expander composition in its electrodes, while the other series of batteries contained a small quantity of alkali-metal sulfite-digested redwood bark solubles in its electrodes. Th batteries which contained the standard battery expander composition in its electrodes stood up for about 3 /2 minutes under this test, whereas the batteries which included the alkali-metal sLdfite-digested redwood bark solubles in its electrodes were able to stand up for about 5 minutes.

Alkali-metal sulfite-digested redwood bark solubles are also useful in tanning liquors. In the process of tanning leather the hides or skins pass through a series of steps in which the hides are acted upon by various tanning liquors. These tanning liquors react with t .e hides so as to preserve the hides and give the finished leather product certain physical qualities, such as color, texture, etc. Quebracho, catechol tannins from chestnut bark, etc., are examples of materials which are commonly used in tanning liquors and which react with the hides in a desired manner.

Alkali-metal sulfite-digested redwood bark solubles have been used in tanning liquors with They havea strong preservative efl'ect on the hides and produce a very desiderable texture in the tanned material, which is very useful if subsequent products such as shoe leather, etc., are to be produced.

It will be understood that the present new composition of matter is not limited to the above enumerated cases which are given for illustrative purposes only.

This application is a continuation in part of our copending application, Serial No. 114,459, filed September 7, 1949.

Various features of the present invention, which are believed to be new, are set forth below.

We claim:

1. As a new composition of matter, alkalimetal sulfite-digested redwood bark solubles said composition consisting essentially of alkali salts of sulfonated redwood bark acids.

2. As a new composition of matter, sodium sulfite-digested redwood bark solubles said composition consisting essentially of sodium salts of sul fonated redwood bark acids.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,229,422 Drewsen June 12, 1917 1,244,525 Marusawa Oct. 30, 1917 1,959,734 Palazzo et al. May 22, 1934 OTHER REFERENCES Lewis et al., Ind. Eng. Chem. 36, 759-764 (1944). Brauns et a1., Paper Trade J., vol. 119, No. 22, pp. 34-38, Nov. 1944. 

1. AS A NEW COMPOSITION OF MATTER, ALKALIMETAL SULFITE-DIGESTED REDWOOD BARK SOLUBLES SAID COMPOSITION CONSISTING ESSENTIALLY OF ALKALI SALTS OF SULFONATED REDWOOD BARK ACIDS. 